(What's In It?)When coconut water broke into the U.S. market 10 years ago, it was billed as a miracle drink able to fight viruses, kidney disease and other ailments like osteoporosis. Global sales now reach $400 million a year, and many consumers believe...

"Here are the nuts," said Drew Sayer, a graduate student in nutrition science, before shoving me into the MRI machine, flat on my back. "Chew them. Swallow them. And don't move your head."I moved my head, which blurred the resulting images. But if all...